Link to Pubmed [PMID] – 31848284
mBio 2019 12;10(6)
is a pathogenic bacterium causing potentially fatal foodborne infections in humans and animals. While the mechanisms used by to manipulate its host have been thoroughly characterized, how the host controls bacterial virulence factors remains to be extensively deciphered. Here, we found that the secreted virulence protein InlC is monoubiquitinated by the host cell machinery on K224, restricting infection. We show that the ubiquitinated form of InlC interacts with the intracellular alarmin S100A9, resulting in its stabilization and in increased reactive oxygen species production by neutrophils in infected mice. Collectively, our results suggest that posttranslational modification of InlC exacerbates the host response upon infection. The pathogenic potential of relies on the production of an arsenal of virulence determinants that have been extensively characterized, including surface and secreted proteins of the internalin family. We have previously shown that the secreted internalin InlC interacts with IκB kinase α to interfere with the host immune response (E. Gouin, M. Adib-Conquy, D. Balestrino, M.-A. Nahori, et al., Proc Natl Acad Sci USA, 107:17333-17338, 2010, https://doi.org/10.1073/pnas.1007765107). In the present work, we report that InlC is monoubiquitinated on K upon infection of cells and provide evidence that ubiquitinated InlC interacts with and stabilizes the alarmin S100A9, which is a critical regulator of the immune response and inflammatory processes. Additionally, we show that ubiquitination of InlC causes an increase in reactive oxygen species production by neutrophils in mice and restricts infection. These findings are the first to identify a posttranscriptional modification of an internalin contributing to host defense.
https://www.ncbi.nlm.nih.gov/pubmed/31848284